Software for Use with Deformity Correction

ABSTRACT

A method of generating a correction plan for correcting a deformed bone includes inputting to a computer system a first image of the deformed bone in a first plane and inputting to the computer system a second image of the deformed bone in a second plane. Image processing techniques are employed to identify a plurality of anatomical landmarks of the deformed bone in the first image. The first image of the deformed bone is displayed on a display device. A graphical of the deformed bone is autonomously generated and graphically overlaid on the first image of the deformed bone on the display device, the graphical template including a plurality of lines, each line connected at each end to a landmark point corresponding to one of the anatomical landmarks. A model of the deformed bone may be autonomously generated based on the graphical template.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/286,757, filed Feb. 27, 2019, which is a continuation of U.S. Pat.No. 10,251,705, filed Jun. 2, 2016, the disclosures of which are eachhereby incorporated by reference herein.

FIELD OF THE INVENTION

The present disclosure relates to software used in planning thecorrection of bone deformities preoperatively and/or postoperatively,and in particular relates to autonomously or semi-autonomously creatingvirtual models to create the correction plan.

BACKGROUND OF THE INVENTION

Currently, external fixation systems may be used to correct skeletaldeformities using the distraction osteogenesis process, for example. TheIlizarov external fixation device (or similar system) may be used forsuch a purpose. The Ilizarov-type devices generally translate bonesegments by manipulating the position of rings connected to each bonesegment.

These external fixation devices generally utilize threaded rods fixatedto through-holes in the rings to build the frame. In order to build thedesired frame, these rods generally have to have different lengths. Oncethe frame is installed, the patient or surgeon moves the rings orpercutaneous fixation components manually or mechanically by adjusting aseries of nuts.

As fixation devices become more complex, the task of determining theoptimal lengths and positions of the struts with respect to rings of thefixation frame, as well as creating a correction plan for manipulatingthe struts to correct the bone deformity, becomes more difficult.

The increasing difficulty of these determinations decreases theattractiveness of using complex fixation frames. It would beadvantageous to have an at least partially automated method fordetermining the optimal configuration of a fixation frame in referenceto a deformed bone, as well as a correction plan for manipulating thefixation frame to correct the bone deformity.

BRIEF SUMMARY OF THE INVENTION

According to a first embodiment of the disclosure, a method ofgenerating a correction plan for correcting a deformed bone includesinputting to a computer system a first image of the deformed bone in afirst plane and inputting to the computer system a second image of thedeformed bone in a second plane. Image processing techniques areemployed to identify a plurality of anatomical landmarks of the deformedbone in the first image. The first image of the deformed bone isdisplayed on a display device. A graphical of the deformed bone isautonomously generated and graphically overlaid on the first image ofthe deformed bone on the display device, the graphical templateincluding a plurality of lines, each line connected at each end to alandmark point corresponding to one of the anatomical landmarks. A modelof the deformed bone may be autonomously generated based on thegraphical template. A first model fixation ring having a first positionand orientation and a second model fixation ring having a secondposition and orientation may be generated and displayed on the displaydevice. At least one of the position and orientation of at least one ofthe model fixation rings may be graphically manipulated.

Combinations of sizes of a plurality of model struts to connect themodels of the first and second fixation rings may be determined with analgorithm using the position and orientation of the first and secondmodel fixation rings. A first position for a limiting anatomicalstructure may be input to the computer system, the limiting anatomicalstructure defining a location having a maximum distraction value. Duringthe step of inputting the first position for the limiting anatomicalstructure, the model rings and the model struts may be simultaneouslydisplayed on the display device and overlap the first image of thedeformed bone on the display device. During the step of inputting thefirst position for the limiting anatomical structure, the first image ofthe deformed bone may include visible soft tissue structures. Thelimiting anatomical structure may be input graphically using an inputdevice, which may be a computer mouse. A second position for thelimiting anatomical structure may be input to the computer system whilethe model rings and the model struts are simultaneously displayed on thedisplay device and overlap the second image of the deformed bone on thedisplay device, the second image of the deformed bone including visiblesoft tissue structures.

Each landmark point of the graphical template may be configured to berepositioned via an input device. Upon repositioning one of the landmarkpoints, each line connected to the repositioned landmark point mayremain connected to the repositioned landmark point.

The first image of the deformed bone may be an x-ray image displayed onthe visual medium in one of an anterior-posterior and a lateral view,and the second image of the deformed bone may be an x-ray imagedisplayed on the visual medium in the other of an anterior-posterior anda lateral view. The first and second images of the deformed bone mayinclude images of physical rings and physical struts of an externalfixation frame coupled to a patient. A position and orientation of thephysical rings and a length and orientation of the physical struts maybe autonomously determined based on the first and second images. Thedetermined position and orientation of the physical rings and thedetermined length and orientation of the physical struts may bedisplayed on the visual medium. At least one of the determined positionand the determined orientation of at least one of the physical rings maybe graphically manipulated. The determined orientation of at least oneof the struts may be graphically manipulated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a home page screen of a deformity correctionapplication.

FIGS. 2A-I illustrate various deformity definition screens of thedeformity correction application.

FIGS. 3A-B illustrate various ring configuration screens of thedeformity correction application in a preoperative (“pre-op”) mode.

FIGS. 4A-B illustrate various strut configuration screens of thedeformity correction application in the pre-op mode.

FIG. 5 illustrates limiting anatomical structure input screen of thedeformity correction application in the pre-op mode.

FIG. 6A illustrates a ring configuration screen of the deformitycorrection application in a postoperative (“post-op”) mode prior to adetermination step.

FIG. 6B illustrates a ring configuration screen of the deformitycorrection application in the post-op mode during the determinationstep.

FIG. 7 illustrates a ring configuration screen of the deformitycorrection application in the post-op mode after the determination step.

FIG. 8 illustrates a limiting anatomical structure input screen of thedeformity correction application in the post-op mode.

DETAILED DESCRIPTION

In one embodiment of the disclosure, software aids a user, such as aphysician, surgeon, or other medical personnel, in planning and carryingout the correction of a bone deformity using a limb reconstruction frameusing a web application, for example. Other software for creating acorrection plan for an external fixation frame is described in U.S.Patent Publication No. 2014/0236153, the contents of which are herebyincorporated by reference herein.

Upon starting the application, the user is presented with a loginscreen. The login screen preferably includes a username field andpassword field in which the user enters, respectively, a username andpassword to gain further access to the application. This step ofauthentication may, for example, help maintain compliance with patientprivacy regulations. In cases where a first time user tries to gainfurther access to the application, a new user account may have to becreated.

As shown in FIG. 1, upon logging in, the user is taken to the homescreen 110. From the home screen 110, the user has the option ofstarting a new case for a patient whose information has not yet beenentered into the software. Prior to starting the new case, the user mayenter a case name and/or number for later reference, and may also enterany desired notes regarding the case to be saved with the case. Askeletal representation 112 may also be provided, for example on thehome screen 110, so that the user may select the relevant bone. As shownin FIG. 1, the left femur has been selected. With the desired anatomyentered, and the relevant case name and number information entered, theuser may choose to begin the case as a pre-op case or a post-op case,with each procedure being described separately below. Generallyspeaking, the pre-op mode is used prior to the surgical fixation of thelimb reconstruction device to the deformed bone. The post-op mode is tobe used after the limb reconstruction device, with associated rings andstruts, has already been affixed to the patient. In a single case, thepre-op mode can be used alone, the post-op mode can be used alone, oreach mode can be used prior to and following surgery, respectively.

After the user begins the case as a pre-op case, the user may be broughtto a case details screen which may allow entering, viewing, or modifyingpatient details such as the patient's name, gender, race, date of birth,anatomy relevant to the case, and notes as the user sees fit. With thecase details entered as desired, the user may begin a deformitydefinition procedure.

The user may be initially presented with a first deformity definitionscreen 200A, as shown in FIG. 2A, which may prompt a user to open orotherwise load one or more medical images, such as X-ray images, ontothe application. Although described herein in terms of X-ray images, itshould be understood that other types of medical images, such as“slices” of a CT-scan, may also be used with the methods and systemsdescribed herein. It should also be understood that multiple medicalimages, such as images of the same anatomy in different views (e.g.anterior-posterior view and lateral view) may be loaded to theapplication. This may be accomplished by any number of suitable methods,for example by choosing one or more image files that have beenpreviously saved to memory on the computer running the application. Inthe pre-op mode, there will generally not be a fixation device shown, asthe fixation device has not yet been implanted onto the patient. Oncechosen, the medical image 201, for example as shown in FIG. 2B, may beshown on a second deformity definition screen 200B. These medical images201 may help the user to define the bone deformity, described more fullybelow. Before, during, or after uploading, the user also may providedetails relating to the image 201, such as the view (e.g. lateral plane)in which the image was taken. With the image 201 shown on screen 200B,the user may scale the image 201 to the application. For example, a sizereference R, such as a ruler, may be included in the image 201, so thatthe user may scale a measurement unit in the application (e.g. a pixel)to a real measurement unit represented in the image 201 (e.g. amillimeter). This step may be performed by the user by selecting adrawing tool, such as a line or circle, and creating a drawing on theimage, preferably in relation to the size reference R. The user mayenter the measurement of the drawn line (or other geometry) thatrepresents the real measurement value, which the application may thencorrelate to the application measurement unit. Alternately, this scalingstep may be performed automatically, for example by the applicationrecognizing a defining characteristic of the size reference R, which maybe compared to a real measurement value already stored in theapplication.

With the image 201 uploaded and scaled, relevant axes of the anatomy maybe defined, either autonomously or semi-autonomously. For example, asshown in FIG. 2C, a user may define, aided by the application, themechanical and/or anatomical axes of the bone(s) against the backdrop ofimage 201 on screen 200C. For example, as shown in FIG. 2C, the user mayselect the “mechanical axis” radio button on screen 200C and using aninput device, may define relevant anatomic landmarks. For example, uponselecting the “mechanical axis” radio button, one (or two) femoralmechanical axis indicia and one (or two) tibial mechanical axis indiciamay appear on the image 201.

In the illustrated embodiment, two mechanical femoral axis indicia takethe form of lines 280, and two mechanical tibial axis indicia take theform of lines 290. Each line 280, 290 may include an endpoint that theuser can drag to a different position on the image 201 to help definethe relevant axes. For example, to define the mechanical femoral axis,the user may drag a first end of line 280 to a center of the femoralhead on one leg and the other end of line 280 to the articular surfaceof the distal femur, and the process may be repeated for the other legif desired. Similarly, to define the mechanical tibial axis, the usermay drag a first end of line 290 to the articular surface of theproximal tibia and the other end of line 290 to the center of the anklejoint. Based on the placement of lines 280 and 290, the application maycalculate and display relevant mechanical axes measurement, for exampleincluding, the lateral proximal femoral angle (“LPFA”), the mechanicallateral distal femoral angle (“mLDFA”), the lateral proximal tibialangle (“LPTA”), and the lateral distal tibial angle (“LDTA”), althoughother relevant measurements may also be calculated and displayed. Inorder to make these measurements, additional lines must be provided. Forexample, the LPFA is measured as the angle between the line joining thetrochanteric tip to the femoral head center 281 and the femoralmechanical axis as represented by line 280. Similarly the mLDFA ismeasured as the angle that a condylar tangent line 282 makes with theline representing the femoral mechanical axis as represented by line280. Lines 281 and 282 may be displayed on the medical image 201 andmanipulated as desired. With regard to the tibial angles, the LPTA ismeasured laterally as the angle between a tibial plateau tangent line291 and the line representing the tibial mechanical axis 290, while theLDTA is measured laterally as the intercept of a tibial articularplafond line 292 with the line representing the tibial mechanical axis290. Lines 291 and 292 may also be displayed on the medical image 201and manipulated by the user. Although the steps above are described asmanual placement of lines 280-282 and 290-292, it should be understoodthat the application may automatically recognize the relevant landmarksand place the lines on the image 201, with the user having the abilityto modify the placement of lines 280-282 and 290-292 if such placementis incorrect. As should be understood, the process may be repeated foreach leg if two legs are shown in medical image 201. The application mayalso compare the calculated angles described above to a range of valuesconsidered normal, which may be stored in memory, and highlight orotherwise indicate to the user any calculated angle falling outside therange. As shown in FIG. 2, the LDTA of the leg with the deformed tibiais calculated as 65°, which is outside a range considered normal, whichmay be for example between 86° and 92°, leading to the abnormal LDTAbeing highlighted.

On a fourth deformity definition screen 200D, the user may select thearea of interest on the medical image 201 for measuring deformityparameters in a following step. For example, a rectangle 270 (or othershape) may be overlaid on the medical image 201 with the option for theuser to resize and/or reposition the rectangle 270 to select therelevant deformed anatomy that is to be corrected. With the relevantarea selected, the image 201 may be modified, for example by croppingthe image so that only the relevant deformed anatomy is displayed, asshown on screen 200E of FIG. 2E. The cropped image 201′ may be furthermodified with a number of image processing features, including, forexample, resizing, repositioning (e.g. rotating), or changing thecontrast of the cropped image 201′. In one example, the user may applyan exposure filter to minimize or eliminate the tissue region shown inthe cropped image 201′ for a better view of the deformed bone. Once thecropped image 201′ is edited as desired, the user may further define thedeformity.

The cropped image 201′ of the deformed right tibia is illustrated inFIG. 2F on a new screen 200F after being rotated and filtered. On screen200F, the mechanical tibia axis 290 from screen 200C may be displayed,along with an anatomical axis 295 a of the proximal tibia and ananatomical axis 295 b of the distal tibia, the axes 295 a and 295 bbeing different due to the deformity. As with the mechanical tibial axis290 described above, the lines representing the anatomical axes 295 a,295 b, may be automatically placed on the cropped image 201′, forexample based upon landmarks of the tibia, with the user having theoption to modify the position of the lines 295 a, 295 b. In addition tothe tibial mechanical axis 290 and the anatomical axes 295 a, 295 b, atemplate 260 may be displayed on the cropped image 201′ to identifylandmarks on the deformed tibia. The template 260 includes a pluralityof landmark points corresponding to anatomical landmarks. In theillustrated example, the template 260 including the medial and lateraledges of the proximal tibial, the center of the proximal tibia, themedial and lateral edges of the distal tibia, and medial and lateralsurfaces of the location of the deformity in the tibia. The template 260may be automatically placed on the cropped image 201′, for example basedupon landmarks of the tibia, with the user having the option of movingone or more of the landmark points to a different position on thecropped image 201′, resulting in the connecting lines repositioning andaltering the shape of template 260. In other words, upon repositioningone of the landmark points, each line connected to the repositionedlandmark point remains connected to the repositioned landmark point.

As shown in FIG. 2G, a radio button may be selected to display a modelbone, in this case a model tibia 202, overlaid on the cropped image201′. The model bone may be selected from a library of model bonesbased, at least in part, on the particular anatomy and patientinformation entered upon creating the case. A button may be clicked onscreen 200G to deform the model bone 202 such that the landmarks of themodel tibia align with the landmarks defined by template 260. Thedeformity may be further defined on deformity definition screen 200H, asshown in FIG. 2H. A line 262 representing the osteotomy plane, and apoint 264 representing the deformity apex, may each be shown on thecropped image 201′, whether or not the model 202 is simultaneously shownon screen 200H. The model bone 202 may include separate proximal anddistal (or reference and moving) portions that may be manipulateddirectly by the user. For example, the user may click one of theportions of model bone 202 and drag the portion into a differentposition, with calculated values (e.g. angulation, translation) updatingas the model bone 202 is manipulated.

Although the deformity definition is described above with reference to amedical image 201 in an anterior-posterior plane, it is preferable thatsome or all of the deformity definition steps are additionally performedon a medical image in a different plane, such as a medial-lateral planeor a superior-inferior plane, for example. The medical image 201 mayalternatively be viewed in axial, coronal or sagittal planes, forexample. As shown in FIG. 2I, the deformed model bone 202 is shown overa cropped image 201′ of the deformed tibia in an AP view and the modelbone 202 is also shown on an adjacent image of the deformed tibia in alateral view. The parameters of the model bone 202, the mechanical andanatomic axes, and the template 260 may be revised in either view toupdate the deformity parameters until the user is satisfied that themodel bone 202 accurately reflects the patient's deformed bone. Asshould be understood from the above description, the system and methodsdescribed herein provide a user the ability to accurately define thedeformity of the deformed bone by manipulating on-screen representationsof the bone or relevant parameters or landmarks with an input device,such as a mouse, without needing to manually enter numerical valuesrelating to the deformity.

Once the user is satisfied that the model bone 202 is an accuraterepresentation of the deformed bone, the user can proceed to the firstring configuration screen 300A (FIG. 3A). At this point, the user mayinput the size of the desired rings, including a reference ring 305 anda moving ring 310. For example, a user may be able to choose between a155 mm, 180 mm, or 210 mm ring. The user may also be able to choose thetype of ring, such as a full ring, partial ring, open ring, or closedring. Different types of rings are known in the art and the inclusion ofdifferent rings as options in the software is largely a matter of designchoice. The rings 305, 310 are displayed along with the model bone 202on the screen, preferably in an AP view, a lateral view, and/or an axialview. Additional views, such as a perspective view, may be included. Onscreen 300A, the model bone 202 and rings 305, 310 are displayed in anAP view with options to change to lateral, axial, and perspective viewsby choosing the corresponding tab on screen. The cropped medical image201′ is also displayed, although either the model bone 202 or thecropped image 201′ may be removed by clicking the appropriate radiobutton on screen.

The position and orientation of portion of the model bone 202 proximalto the deformity and the portion of the model bone 202 distal to thedeformity are based on the input received during the deformitydefinition described above. Once a size and/or type of ring is selectedfor the reference ring 305, it is displayed perpendicular to thereference bone fragment (in the illustrated example, the portion of themodel bone 202 proximal to the deformity) with a longitudinal axis ofthe reference bone fragment extending through the center of thereference ring 305. Similarly, once a size and/or type of ring isselected for the moving ring 310, it is displayed perpendicular to thenon-reference bone fragment (in the illustrated example, the portion ofthe model bone 202 distal to the deformity) with a longitudinal axis ofthe non-reference bone fragment extending through the center of themoving ring 310. The rings 305, 310 may also be placed with a defaultaxial translation that can be changed. For example, the reference ring305 may have a default axial translation of approximately 50 mm withrespect to the deformity apex, while the moving ring 210 may have adefault axial translation of approximately 150 mm with respect to thedeformity apex. The user may enter numerical values for position andorientation parameters for the rings 305, 310, by inputting values,clicking the “up” or “down” arrows associated with the particularposition or orientation, or by interacting with the rings 305, 310 onscreen, for example by clicking one of the rings 305, 310 with a mouseand dragging or rotating the ring to a new position and/or orientation.Because this is the pre-op mode and no fixation devices has yet beenattached to the patient, the user chooses the ring sizes, positions andorientations that he believes will be effective for the correctionbased, for example, on his experience and knowledge. As the values forthe position and/or orientation of the rings 305, 310 are changed, thegraphical representations of the rings 305, 310 changes to reflect thenew values. If the rings 305, 310 are being manipulated graphically(e.g. via dragging on screen with a mouse), the numerical valuesassociated with the position and/or orientation may update accordingly.For the reference ring 305, the position values may include an APtranslation, a lateral translation, an axial translation, and an axialorientation. The moving ring 310 may include these values, andadditional values may include an AP orientation and a lateralorientation. Any of the above-described values may be displayed onscreen to assist the user in understanding the position of the rings305, 310 relative to the model 202. It may be particularly useful todisplay only non-zero values so that the most pertinent information isdisplayed. The user may position multiple views of the model bone 202and the rings 305, 310 on the screen simultaneously. For example, asshown in FIG. 3B, screen 300B illustrates the model bone 202 with rings305, 310 positioned thereon simultaneous in the AP and lateral viewswith the cropped image 201′ hidden.

Once the user is satisfied that the reference ring 305 and moving ring310 are at locations on the model bone 202 representative of where theactual rings should be located on the patient's deformed bone, the usercan proceed to the first strut configuration screen 400A as shown inFIG. 4A. The first strut configuration screen 400A allows the user toinitiate an automatic calculation of possible strut combinations toconnect the reference ring 305 to the moving ring 310. Once thecalculation is complete, a plurality of graphical representations ofstruts 410 are illustrated on the screen in their intended initialpositions with respect to the graphical representation of the referencering 305 and the moving ring 310. The user also has the option todisplay all of the calculated combinations of struts 410 that may beused with the external fixator. For example, although one particularcombination of struts 410 is illustrated on screen, multiplecombinations may be calculated as possibilities. The application maydefault to showing the combination of struts 410 that requires thefewest number of strut change-outs during the deformity correction, butother options may be available for the user to choose based on his orher particular desire. The possible strut combinations may be presentedin a table with a description of each strut in a particular combination.

As with the other planning stages described above, the user may causeother views of the model bone 202, rings 305, 310 and struts 410 to beillustrated on screen, either individually or simultaneously. Forexample, the model bone 202, rings 305, 310, and struts 410 are shown inthe AP, lateral, axial, and perspective views on screen 400B in FIG. 4B.This may help the user better visualize the external fixator system.When a particular combination of strut 410 is selected, the orientationof each strut 410, including strut length and strut angle, may bedisplayed. After the user is satisfied with the selected combination ofstruts 410, the user may proceed to a limiting anatomical structure(“LAS”) input screen 500.

The LAS input screen 500 (FIG. 5) allows a user to input a position fora limiting anatomical structure. In particular, the user may input avalue (or the application may provide a default value) for a maximumdistraction rate, which is the maximum distance a structure may moveover time. For example, nerves, soft tissue, or even ends of the bonemay be damaged if the rate of distraction at these points is too great.The user may define a LAS point 510 on screen 500 by dragging the LASpoint 510 to the desired position. This step may be done both the AP andlateral views to define the LAS point 510 in three dimensions. The LASpoint 510 defines a position that cannot be have a distraction rategreater than the maximum distraction rate, so that the anatomy at theLAS point 510 does not distract too quickly during correction and becomedamaged. For example, neurovascular tissue may sustain stretch damage ifthe tissue experiences too great a distraction rate. Although a user maychoose the position of the LAS point 510 based on his experience and themodel bone 202 on screen 500, it would be helpful to the user to be ableto visualize soft tissue when defining the position of the LAS point 510as soft tissue may be the anatomy at risk of damage from the deformitycorrection. To that end, when defining the position of the LAS point510, the cropped image 201′ may be unhidden, with one or more of themodel bone 202, rings 305, 310, and struts 410 simultaneously beingshown on screen 500. By editing the parameters of cropped image 201′,for example by adjusting the contrast or exposure as described above,the user may view the patient's soft tissue in addition to the deformedbone on a screen with the models of the bone 202, rings 305, 310, and/orstruts 410. The visualization of the soft tissue may aid the user inprecisely defining the LAS point 510 to reduce the chance of injury tothe patient's LAS during correction of the deformed bone.

Based on the position and orientation of the model bone 202, the rings305, 310, the struts 410, and the position of the LAS point 510, theuser may generate the correction plan. To generate the correction plan,the user may enter the date on which the user or patient will beginadjusting the fixation frame according to the correction plan. Onceentered, the user commands the computer to generate the correction plan,which may be displayed on screen. The correction plan may include, forexample, the position and angle of each strut of the fixation frame foreach day of the correction, along with the date and day number (e.g.first day, second day) of the correction plan. The correction plan mayalso show a relationship between positions of the struts and discreteuser or patient actions. For example, if the correction plan calls for astrut to be lengthened by 1 millimeter on the first day, the correctionplan may indicate that the user or patient should increase the length ofthat strut four separate times, for example by 0.25 millimeters in themorning, 0.25 millimeters at noon, 0.25 millimeters in the evening andanother 0.25 millimeters at night. Besides use as an instructional tool,the correction plan may also aid a physician or surgeon in monitoringthe progress of the correction of the bone deformity, for example bychecking at periodic intervals that the struts of the fixation frame arein the proper position as called for by the correction plan.

As mentioned above, the application can be used in a post-op mode inaddition or as an alternative to the pre-op mode. This mode can be usedonce the patient has already undergone surgery to attach the fixationframe to the deformed bone. The post-op mode can be used as analternative to the pre-op mode, for example in cases in which time islimited and surgery must be performed without the benefit of theplanning provided in the pre-op mode described above. However, thepost-op mode can be used in addition to the pre-op mode, if thephysician was unable to affix the fixation frame to the bone assuggested by the pre-op mode.

In the post-op mode, the steps described above with reference to thelogin screen and home page 110 are the same as in the pre-op mode (FIG.1). In order to generate an accurate post-op correction plan thatminimizes the risk of misalignment of the deformed bone and/or damage totissue, accurate models of the mounted frame should be created in theapplication. Any misinterpretations or calculation errors during themodeling process can affect the correction plan. Thus, it would bebeneficial for the application to assist the user in creating the modelrings 305, 310 and struts 410 to generate the model parameters asaccurately as possible, preferably while minimizing user intervention.As described below, the application is capable of recognizing theanatomical structures and frame components in the medical image 201 (orcropped image 201′) by using image processing algorithms and coordinategeometry theories to provide accurate measurements of the fixation frameand anatomy, either in a fully autonomous or semi-autonomous fashion.

Similar to the pre-op mode, after entering the relevant patient details,the user can upload one or more medical images 201 in one or more viewsto the application. Because this is a post-op mode, uploaded medicalimages 201 show the physical rings and struts of the fixation frame, asthey have already been attached to the patient's bone. The process ofinputting the measurements in the deformity definition step may be thesimilar or the same as described with respect to the pre-op mode. Forexample, as shown in FIG. 6A, a first screen 600A may include scalingthe medical images 201. A size reference R with a known size may beincluded in the medical image 201, with the known size stored in memoryso that the application is able to automatically scale each medicalimage 201 to the correct size.

With each medical image 201 properly scaled, the user may initiate aprocessing step in which the application determines the size andorientations of the physical reference ring 605, the physical movingring 610, and the physical struts 710. The application may process themedical images 201, with a first recognition stage employing textureguided shape analysis algorithms that recognize and identify thestructures based on textures and/or shapes in the images 201. Oncerecognized, the application employs projective geometry techniques todetermine the position and orientation of the physical rings 605, 610and physical struts 710. This step may include the calculation of theradius (or diameter) of each physical ring 605, 610, the angularorientations of each ring 605, 610, the length of each physical strut710, the angular orientation of each physical strut 710, and theconnection points of each strut 710 to each ring 605, 610.

In addition to recognizing the components of the physical fixationsystem and determining the position and orientation of the components,the application may also recognize the patient's bone structures as wellas the position and orientations of relevant fragments. During thisstep, the application recognizes a reference fragment (as illustrated onscreen 600B of FIG. 6B, this is the bone fragment proximal to thedeformity) and a moving fragment (as illustrated on screen 600B of FIG.6B, this is the bone fragment distal to the deformity). The bonestructures may be recognized using image processing techniques that usestructural and textural features along with machine learning techniques,including, for example, statistical shape modelling. Subspace analysistechniques for bone detection may make use of shape, texturedistributions, and kernel method based learning techniques for accurateextraction of anatomical structures. During or after the automaticrecognition of the fixation frame components and the bone fragments,indicia I may be provided on screen to indicate the structures asidentified by the application. As shown in FIG. 6B, such indicia I mayinclude one or more points along the physical reference ring 605, one ormore points along the physical moving ring 610, and one or more relevantpositions of the bone.

Once the identification step and position and orientation recognitionsteps are completed for both the physical frame components and the bonefragments, the relevant parameters are displayed on a ring configurationscreen 700 as shown in FIG. 7. Relevant parameters, which may be thesame as those described with respect to the pre-op mode and FIG. 3B, maybe displayed so that the user is able to confirm that the calculationsperformed by the application are correct. If the user desires to alterany of the parameters, he may use an input device (e.g. a mouse orkeyboard) to activate the “up” or “down” arrow on screen 700 next to therelevant parameter to increase or decrease the parameter, or use theinput device to graphically change one of the lines representing therelevant parameter on the image 201. The user may similarly confirm orrevise relevant parameters calculated with respect to the physicalstruts 710 on a strut configuration page (not shown). Finally, the usermay advance to a LAS input page 800, as shown in FIG. 8, to indicate theposition of the LAS point 810. The procedure regarding the input of theposition of the LAS point 810 may be the same as described in connectionwith FIG. 5 in the pre-op mode.

As mentioned above, although the application preferably automaticallyand correctly identifies the bone fragments, the physical components ofthe fixation frame, and the positions and orientations of the fragmentsand components. To the extent that the user desires to change theautomatically determined identifications, positions, and orientations ofthe frame components, he may do so as described above with respect toFIGS. 7-8 by adjusting the parameters on screen. With regard to the bonefragments, upon the identification and determination of the position ofthe fragments, the application may display the template 260 over themodel bone 202 (and/or medical image 201) similar to that shown anddescribed in connection to FIGS. 2F-G in the pre-op mode. In fact, thisautomatic recognition process may be used when initiating the deformitymeasurement in the pre-op mode as well. To the extent the user desiresto alter the automatically populated template, he may alter the templategraphically by moving the relevant landmarks of the template similar tothe method described in connection with FIGS. 2F-G.

Once the user is satisfied that the automatically calculated positionsand orientations of the physical components of the frame and the bonefragments are accurate, or after adjusting the calculated positions andorientations to the user's satisfaction, and also after inputting theposition of the LAS point 810, the user may generate a correctionschedule in the same manner as described above with respect to thepre-op mode.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. For example, although described in relation to acorrection of a deformed tibia, other bones and fixation frames forthose bones may be modeled by the application according to the sameprinciples described above. It is therefore to be understood thatnumerous modifications may be made to the illustrative embodiments andthat other arrangements may be devised without departing from the spiritand scope of the present invention as defined by the appended claims.

1. A method of generating a correction plan for correcting a deformedbone comprising the steps of: inputting to a computer system a firstx-ray image of the deformed bone in a first plane, the deformed boneincluding a proximal fragment and a distal fragment, the first imageshowing a physical proximal fixation ring coupled to the proximalfragment, a physical distal fixation ring fixed to the distal fragment,and a plurality of physical struts coupling the physical proximalfixation ring to the physical distal fixation ring; displaying the firstx-ray image on a display device; generating a representation of theproximal fragment on the display device; generating a representation ofthe distal fragment on the display device; displaying a model proximalfixation ring overlying the proximal fragment in the first x-ray imageon the display device, the model proximal fixation ring having aposition; displaying a model distal fixation ring overlying the distalfragment in the first x-ray image on the display device, the modeldistal fixation ring having a position; using the first x-ray imagedisplayed on the display device to determine a length and orientation ofeach of the plurality of physical struts; displaying a representation ofeach of the plurality of physical struts having a length and orientationthat corresponds to the length and orientation of corresponding ones ofthe plurality of physical struts; and generating the correction planbased at least on a position of the representation of the proximalfragment, a position of the representation of the distal fragment, theposition of the model proximal fixation ring, the position of the modeldistal fixation ring, and the determined length and orientation of eachof the plurality of physical struts.
 2. The method of claim 1, whereinusing the first x-ray image displayed on the display device to determinethe length and orientation of each of the plurality of physical strutsis performed automatically by the computer system.
 3. The method ofclaim 1, wherein generating the representation of the proximal fragmentincludes generating a first line overlying a central axis of theproximal fragment in the first x-ray image on the display device.
 4. Themethod of claim 3, wherein the first line overlying the central axis ofthe proximal fragment in the first x-ray image on the display deviceincludes a first endpoint corresponding to a first anatomical landmarkin the proximal fragment.
 5. The method of claim 3, wherein generatingthe representation of the distal fragment includes generating a firstline overlying a central axis of the distal fragment in the first x-rayimage on the display device.
 6. The method of claim 5, wherein thesecond line overlying the central axis of the distal fragment in thefirst x-ray image on the display device includes a second endpointcorresponding to a second anatomical landmark in the distal fragment. 7.The method of claim 1, wherein generating the representation of theproximal fragment includes displaying a virtual proximal bone fragmentmodel on the display device.
 8. The method of claim 7, whereingenerating the representation of the distal fragment includes displayinga virtual distal bone fragment model on the display device.
 9. Themethod of claim 1, further comprising changing the position of the modelproximal fixation ring with respect to the proximal fragment on thedisplay device.
 10. The method of claim 9, further comprising changingthe position of the model distal fixation ring with respect to thedistal fragment on the display device.
 11. The method of claim 10,wherein the steps of changing the position of the model proximalfixation ring with respect to the proximal fragment on the displaydevice and changing the position of the model distal fixation ring withrespect to the distal fragment on the display device are performedgraphically on the display device.
 12. A method of generating acorrection plan for correcting a deformed bone comprising the steps of:inputting to a computer system a first x-ray image of the deformed bonein a first plane, the deformed bone including a proximal fragment and adistal fragment, the first image showing a physical proximal fixationring coupled to the proximal fragment, a physical distal fixation ringfixed to the distal fragment, and a plurality of physical strutscoupling the physical proximal fixation ring to the physical distalfixation ring; displaying the first x-ray image on a display device;generating a representation of the proximal fragment on the displaydevice; generating a representation of the distal fragmenton the displaydevice; displaying a model proximal fixation ring overlying the proximalfragment in the first x-ray image on the display device, the modelproximal fixation ring having a position; displaying a model distalfixation ring overlying the distal fragment in the first x-ray image onthe display device, the model distal fixation ring having a position;using the first x-ray image displayed on the display device to determinefirst connection points between a first end of each of the plurality ofphysical struts and the physical proximal fixation ring, and secondconnection points between a second end of each of the plurality ofphysical struts and the physical distal fixation ring; determining alength and orientation of each of the plurality of physical struts;displaying a representation of each of the plurality of physical strutshaving a length and orientation that corresponds to the length andorientation of corresponding ones of the plurality of physical struts;and generating the correction plan based at least on a position of therepresentation of the proximal fragment, a position of therepresentation of the distal fragment, the position of the modelproximal fixation ring, the position of the model distal fixation ring,and the determined length and orientation of each of the plurality ofphysical struts.
 13. The method of claim 12, wherein determining thelength and orientation of each of the plurality of physical struts isperformed automatically by the computer system.
 14. The method of claim12, wherein generating the representation of the proximal fragmentincludes generating a first line overlying a central axis of theproximal fragment in the first x-ray image on the display device. 15.The method of claim 14, wherein the first line overlying the centralaxis of the proximal fragment in the first x-ray image on the displaydevice includes a first endpoint corresponding to a first anatomicallandmark in the proximal fragment.
 16. The method of claim 14, whereingenerating the representation of the distal fragment includes generatinga first line overlying a central axis of the distal fragment in thefirst x-ray image on the display device.
 17. The method of claim 16,wherein the second line overlying the central axis of the distalfragment in the first x-ray image on the display device includes asecond endpoint corresponding to a second anatomical landmark in thedistal fragment.
 18. The method of claim 12, wherein generating therepresentation of the proximal fragment includes displaying a virtualproximal bone fragment model on the display device.
 19. The method ofclaim 18, wherein generating the representation of the distal fragmentincludes displaying a virtual distal bone fragment model on the displaydevice.
 20. The method of claim 12, further comprising changing theposition of the model proximal fixation ring with respect to theproximal fragment on the display device.
 21. The method of claim 20,further comprising changing the position of the model distal fixationring with respect to the distal fragment on the display device.
 22. Themethod of claim 21, wherein the steps of changing the position of themodel proximal fixation ring with respect to the proximal fragment onthe display device and changing the position of the model distalfixation ring with respect to the distal fragment on the display deviceare performed graphically on the display device.